Worldwide Interoperability for Microwave Access (WiMAX) is a telecommunications technology often aimed at providing wireless data over long distances (e.g., kilometers) in a variety of ways, from point-to-point links to full mobile cellular type access. A network based upon WiMAX is occasionally also called a Wireless Metropolitan Access Network (WirelessMAN or WMAN); although, it is understood that WMANs may include protocols other than WiMAX. WiMAX often includes a network that is substantially in compliance with the IEEE 802.16 standards, their derivatives, or predecessors (hereafter, “the 802.16 standard”). Institute of Electrical and Electronics Engineers, IEEE Standard for Local and Metropolitan Area Networks, Part 16, IEEE Std. 802.16-2004.
One particular derivative of the 802.16 standard is the 802.16m standard that attempts to increase the data rate of wireless transmissions to 1 Gbps while maintaining backwards compatibility with older networks. IEEE 802.16 Broadband Wireless Access Working Group, IEEE 802.16m System Requirements, Oct. 19, 2007.
Wireless Local Area Network (WLAN) is a telecommunications technology often aimed at providing wireless data over shorter distances (e.g., meters or tens of meters) in a variety of ways, from point-to-point links to full mobile cellular type access. A network based upon the WLAN standard is occasionally also referred to by the common or marketing name “WiFi” (or “Wi-Fi”) from Wireless Fidelity; although it is understood that WLAN may include other shorter ranged technologies. WiFi often includes a network that is substantially in compliance with the IEEE 802.11 standards, their derivatives, or predecessors (hereafter, “the 802.11 standard”). Institute of Electrical and Electronics Engineers, IEEE Standard for Information Technology—Telecommunications and Information Exchange between Systems—Local and Metropolitan Area Network—Specific Requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, IEEE Std. 802.11-2007.
Multiple-input and multiple-output (MIMO), is generally the use of multiple antennas at both a transmitter and a receiver to improve communication performance. It is often considered one of several forms of smart antenna technology. MIMO technology frequently offers significant increases, compared to single input/output technology, in data throughput and link range without additional bandwidth or transmit power. MIMO systems generally achieve this by higher spectral efficiency (e.g., more bits per second per hertz of bandwidth) and link reliability or diversity (e.g., reduced fading). In general, Close Loop (CL) multi-user (MU) MIMO systems require feedback of communications channel information from all the active users. The feedback overhead however, often decreases the efficiency of the MU-MIMO system capacity.
A frequent cellular network implementation may have multiple antennas at a base station (BS) and a single antenna on the mobile station (MS). In such an embodiment, the cost of the mobile radio may be minimized. As the costs for radio frequency (RF) components in mobile station are reduced, second antennas in mobile device may become more common. Multiple mobile device antennas may currently be used in Wi-Fi technology (e.g., IEEE 802.11n).